A triphenylamine/Ir(III) bis terpyridine dyad for the assembly of a charge separation construct with improved performances

A new dyad DII-Ir consisting of a triphenylamine donor and a bis(terpyridine)IrIII acceptor separated by a bridge composed of two benzamide groups has been synthesized. The electrochemical and photophysical properties of the dyad have been compared to those of a corresponding dyad D-Ir characterized by a bridge connecting the donor and the acceptor consisting of a single benzamide unit. We show that, whereas the charge-separation steps are still very efficient in the long dyad (99 %), charge recombination is slowed by a factor of three with respect to the short dyad. This encourages the use of this dyad in the assembly of a more elaborate array DII-Ir-A, expected to overcome the disappointingly low charge-separation yield of a previously studied D-Ir-A short triad.